fix conversation read/unread edge cases

A re-render should mark new messages read, if there are any.
* on rotate, all messages will stay read, so nothing will
  happen in that case

A re-render should not clear 'unread' state as far as
"mark unread", i.e. "New message from X" -> tap -> re-render
-> mark unread -> should mark ALL unread messages unread, not
just new ones.

Bug: 7026808
Change-Id: I4693481a0a3e6d89380f9d16fd8591ba179896b2
2 files changed